695  
FXUS02 KWBC 251901  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 PM EST TUE JAN 25 2022  
 
VALID 12Z FRI JAN 28 2022 - 12Z TUE FEB 01 2022  
 
...COASTAL WINTER STORM THREAT FROM THE MID-ATLANTIC TO ESPECIALLY  
NEW ENGLAND FRIDAY INTO THE WEEKEND...  
 
   
..OVERVIEW
 
 
AT THE BEGINNING OF THE MEDIUM RANGE PERIOD LATE THIS WEEK, DEEP  
TROUGHING WILL TRAVERSE THE EASTERN HALF OF THE U.S. AND SPIN UP A  
SIGNIFICANT AND RAPIDLY DEEPENING SURFACE LOW IN THE WESTERN  
ATLANTIC. THIS STRONG COASTAL STORM MAY CAUSE HEAVY SNOW IN THE  
COASTAL MID-ATLANTIC REGION WITH MORE CERTAINTY FOR HEAVY SNOW  
OVER THE NORTHEAST, WHERE HIGH WINDS AND COASTAL FLOODING ARE ALSO  
LIKELY THROUGH THE WEEKEND. MEANWHILE, INITIAL RIDGING IN THE WEST  
WILL BE SOMEWHAT DISRUPTED BY PACIFIC ENERGY TRACKING EASTWARD  
OVER THE WEEKEND, BEFORE A MORE POTENT TROUGH DIGS INTO THE WEST  
EARLY IN THE WORKWEEK AND FINALLY FLIPS THE OVERALL UPPER PATTERN  
SOMEWHAT WITH DECREASING HEIGHTS OVER THE WEST AND RISING HEIGHTS  
OVER THE EAST.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT GUIDANCE IS STILL ON TRACK WITH A SIGNIFICANT LOW PRESSURE  
SYSTEM IN THE WESTERN ATLANTIC LATE THIS WEEK, THOUGH WITH SOME  
BOUNCING AROUND IN THE EXACT PLACEMENT OF THE LOW AND ITS TRACK.  
SOURCES OF THIS UNCERTAINTY INCLUDE SEVERAL UPSTREAM SHORTWAVES (A  
COUPLE MOVING THROUGH THE GREAT LAKES REGION AND ONE DIVING  
APPROXIMATELY THROUGH THE ROCKIES WEDNESDAY NIGHT-THURSDAY NIGHT)  
THAT AFFECT THE DEVELOPMENT OF THE UPPER-LEVEL TROUGH. THESE  
FINE-SCALE FEATURES WILL STILL TAKE A WHILE TO BE RESOLVED  
SATISFACTORILY. IN GENERAL, 00Z/06Z GUIDANCE SHOWED A SLIGHTLY  
EASTERN TRACK COMPARED TO THE PREVIOUS RUNS, BUT WITH THE  
EXCEPTION OF THE DETERMINISTIC ECMWF AND TO A LESSER EXTENT THE EC  
MEAN ON THE WESTERN SIDE. CLUSTER ANALYSIS AND PLOTS OF INDIVIDUAL  
ENSEMBLE LOWS SHOWED THAT THE EC SUITE OF GUIDANCE WAS PRETTY  
CONSISTENTLY FARTHER WEST AS THE LOW DEVELOPS THAN THE  
DETERMINISTIC GFS RUNS AND GEFS AND CMC ENSEMBLE MEMBERS, GIVEN AN  
EC WIDER TROUGH BUMPING UP TO A BIT MORE OF AN UPSTREAM RIDGE IN  
THE ATLANTIC SO A LOW WRAPS IN. HOWEVER, THEN THE 12Z GFS, GEFS  
MEAN, AND CMC CAME IN WITH A SLIGHT WESTWARD SHIFT IN THE LOW  
TRACK, THOUGH NOT QUITE AS FAR WEST AS THE 00Z AND NEW 12Z ECMWF.  
SO, THE STRATEGY OF TAKING A MIDDLE GROUND POSITION WITH THE LOW  
BETWEEN THE WESTERN/EASTERN EXTREMES SEEMS TO HAVE WORKED WELL,  
AND THIS WAS SIMILAR TO THE PREVIOUS FORECAST POSITION OF THE LOW.  
THIS FORECAST TRACK ALSO SHOWS MORE SNOW AS THE DOMINANT  
PRECIPITATION TYPE RATHER THAN SLEET/FREEZING RAIN.  
 
MODELS AGREE REGARDING RIDGING IN THE WEST INITIALLY ON FRIDAY,  
WITH A COMPACT POSSIBLY CLOSED LOW IN THE EASTERN PACIFIC. THIS  
RELATIVELY SMALL FEATURE COULD STILL LEAD TO PREDICTABILITY ISSUES  
FOR A WHILE AS IT TRACKS EASTWARD INTO THE SOUTHWEST THIS WEEKEND  
AND WITH LESS CERTAINTY BEYOND THEN. THE GFS RUNS AND ECMWF START  
OUT IN GOOD AGREEMENT WHILE THE 00Z CMC DID NOT CLUSTER WELL WITH  
CONSENSUS (THE 12Z RUN LOOKS BETTER). BY EARLY NEXT WEEK, GFS RUNS  
KEPT STRONGER ENERGY FARTHER NORTH COMPARED TO A WEAKENING EC  
FEATURE IN SOUTH TEXAS EARLY MONDAY.  
 
THE LARGER SCALE UPPER TROUGH EVENTUALLY REACHING INTO THE WESTERN  
U.S. WILL BE FROM SOME COMBINATION OF PROGRESSIVE NORTH PACIFIC  
ENERGY AND FLOW DESCENDING FROM ALASKA. DIFFERENCES BY DAY  
7/TUESDAY ARE WITHIN THE REALM OF TYPICAL GUIDANCE SPREAD/ERROR AT  
THAT TIME FRAME BUT DIFFERENCES REMAIN IN ITS EVOLUTION.  
 
THE WPC FORECAST EARLY IN THE PERIOD USED A BLEND FAVORING THE GFS  
AND ECMWF RUNS AS WELL AS CONTINUITY, WITH AN ATLANTIC LOW  
POSITION GENERALLY IN BETWEEN THE DETERMINISTIC GUIDANCE AND SOME  
MANUAL ENHANCEMENT IN TERMS OF THE CENTRAL PRESSURE. INCREASED THE  
PROPORTION OF ENSEMBLE MEANS BY THE END OF THE PERIOD TO RESOLVE  
SOME OF THE TIMING AND DETAIL DIFFERENCES THAT ARISE.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
KEY MESSAGES FOR JANUARY 28-30 (FRIDAY-WEEKEND) WINTER STORM:  
CONFIDENCE IS INCREASING THAT A SIGNIFICANT WINTER STORM WILL  
CREATE CONSIDERABLE IMPACTS FRIDAY THROUGH THE WEEKEND FROM THE  
MID-ATLANTIC THROUGH THE NORTHEAST. HEAVY SNOW IS MOST LIKELY IN  
PARTS OF NEW ENGLAND. HEAVY SNOW IS STILL POSSIBLE FURTHER SOUTH  
ON THE EAST COAST, INCLUDING THE MAJOR I-95 METROPOLITAN AREAS  
FROM NEW YORK CITY TO WASHINGTON D.C., BUT THAT IS MORE UNCERTAIN  
AT THIS TIME. SIGNIFICANT COASTAL IMPACTS ARE POSSIBLE IN THE  
NORTHEAST, INCLUDING COASTAL FLOODING AND BEACH EROSION.  
ADDITIONALLY, STRONG WINDS MAY CAUSE BLOWING SNOW AND SOME DAMAGE.  
HAZARDOUS TRAVEL CONDITIONS ARE LIKELY IN PARTS OF THE REGION.  
PLEASE CONTINUE TO MONITOR FOR UPDATES, AND CHECK YOUR LOCAL  
FORECAST AT WEATHER.GOV.  
 
OTHER WEATHER HIGHLIGHTS:  
CURRENTLY IT APPEARS THAT THE UPPER TROUGH/LOW THAT MAY TRACK INTO  
CALIFORNIA AND THE SOUTHWEST THIS WEEKEND COULD BE WEAK ENOUGH NOT  
TO PRODUCE MUCH IF ANY PRECIPITATION OVER THAT REGION. ITS  
STRENGTH AND TRACK THEREAFTER WILL DETERMINE HOW MUCH  
PRECIPITATION MAY DEVELOP FROM THE GULF COAST NORTHWARD BY THE  
FIRST PART OF NEXT WEEK. CONFIDENCE IS VERY LOW GIVEN A WIDE ARRAY  
OF POSSIBILITIES BETWEEN MEANINGFUL AMOUNTS AND DRY CONDITIONS.  
AHEAD OF THE NORTHEASTERN PACIFIC UPPER TROUGH, MOISTURE SHOULD  
BEGIN TO MOVE INTO THE NORTHWEST ON SUNDAY AND THEN CONTINUE TO  
SPREAD ACROSS MORE OF THE WEST WITH TIME. HIGHEST TOTALS OF  
RAIN/MOUNTAIN SNOW SHOULD BE OVER THE PACIFIC NORTHWEST, BUT  
AMOUNTS DO NOT APPEAR TOO SIGNIFICANT AT THIS TIME. A SERIES OF  
WAVES/FRONTS MAY BRING EPISODES OF LIGHT AND SCATTERED SNOW INTO  
PARTS OF THE GREAT LAKES.  
 
MUCH OF THE EASTERN HALF OF THE COUNTRY WILL BE QUITE CHILLY  
THROUGH THE WEEKEND, WITH SATURDAY-SUNDAY HAVING THE BROADEST  
COVERAGE OF TEMPERATURES 10-20F BELOW NORMAL. EXPECT A WARMING  
TREND TO BRING READINGS BACK CLOSE TO NORMAL BY MONDAY OR TUESDAY.  
MUCH OF THE PLAINS WILL SEE ABOVE NORMAL TEMPERATURES (UP TO PLUS  
10-20F ANOMALIES) LATE THIS WEEK INTO MONDAY, ASIDE FROM A COOL  
FRIDAY OVER FAR SOUTHERN AREAS. NORTHERN LOCATIONS WILL SEE A  
COLDER TREND MONDAY-TUESDAY WHILE THE RELATIVE WARMTH FARTHER  
SOUTH SPREADS A BIT FARTHER EASTWARD. THE WEST SHOULD SEE PLUS  
5-10F OR SO ANOMALIES THROUGH THE WEEKEND FOLLOWED BY A COOLER  
TREND EARLY NEXT WEEK AS UPPER TROUGHING MOVES IN.  
 
TATE/RAUSCH  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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